Five years ago, a bunch of individuals in Wuhan, China, became sick with a virus never seen before on this planet.

The germ had neither a reputation nor the disease it could cause. It ultimately sparked a pandemic that exposed deep inequities in the worldwide health system and shifted public opinion about the way to combat deadly emerging viruses.

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The virus remains to be with us, although humanity has built up immunity through vaccinations and infections. It is less deadly than it was at first of the pandemic and isn’t any longer at the highest of the list of leading causes of death. But the virus is evolving, meaning scientists must track it closely.

Where does the SARS-CoV-2 virus come from?

We don't know. Scientists consider the most probably scenario is that, like many coronaviruses, it circulated in bats. They assume it then probably infected one other species Raccoon dogsCivet cats or bamboo rats, which in turn infected individuals who handled or slaughtered these animals at a market in Wuhan, where the primary Human cases occurred in late November 2019.

This is a widely known route of disease transmission and sure caused the primary epidemic of an identical virus, referred to as SARS. However, this theory has not been proven for the virus that causes COVID-19. There are several research laboratories in Wuhan dedicated to collecting and studying coronaviruses, fueling debate about whether the virus can have leaked from a lab.

It is a difficult scientific puzzle to resolve under the very best of circumstances. The effort has been made even tougher by political scrutiny of the virus's origins and international researchers say China is attempting to withhold evidence that would help.

The true origin of the pandemic is probably not known for a few years, if ever.

How many individuals have died from COVID-19?

Probably greater than 20 million. According to the World Health Organization, member countries have reported greater than 7 million deaths from COVID-19, however the actual death toll is estimated to be at the very least thrice that.

An average of about 900 people per week within the U.S. have died from COVID-19 over the past yr, based on the U.S. Centers for Disease Control and Prevention.

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Older people proceed to be most affected by the coronavirus. People ages 75 and older accounted for about half of COVID-19 hospitalizations and hospital deaths within the U.S. last winter, based on the CDC.

“We cannot talk about COVID in the past as it is still with us,” said WHO director Tedros Adhanom Ghebreyesus.

Which vaccines have been made available?

Scientists and vaccine makers have broken speed records developing COVID-19 vaccines which have saved tens of tens of millions of lives worldwide – and represented the crucial step toward returning life to normal.

Less than a yr after China identified the virus, health authorities within the United States and Britain released the Pfizer and Moderna vaccines. Years of previous research – including Nobel Prize discoveries which were key to creating the brand new technology work – gave the so-called mRNA vaccines a head start.

Today there may be also a more traditional vaccine from Novavax, and a few countries have tried additional options. The rollout to poorer countries has been slow, however the WHO estimates that greater than 13 billion doses of COVID-19 vaccines have been administered worldwide since 2021.

The vaccines are usually not perfect. They do job of stopping serious illness, hospitalization, and death and have been shown to be very secure, with rare serious negative effects. But after a number of months, protection against minor infections wears off.

Like flu vaccines, COVID-19 vaccinations should be updated frequently to accommodate the ever-evolving virus — adding to the general public's frustration over the necessity for repeated vaccinations. Efforts are underway to develop next-generation vaccines, similar to nasal vaccines, that researchers hope shall be higher at blocking infections.

Which variant dominates now?

Scientists named these variants after Greek letters: Alpha, Beta, Gamma, Delta and Omicron. Delta, which became prevalent within the United States in June 2021, was a serious concern since it was twice as more likely to end in hospitalization as the primary version of the virus.

Then, at the tip of November 2021, a brand new variant got here onto the market: Omicron.

“It spread very quickly,” said Dr. Wesley Long, a pathologist at Houston Methodist in Texas, and dominated inside a number of weeks. “Compared to anything we had seen before, this resulted in a huge increase in cases.”

But on average, the WHO said, it caused less severe illness than Delta. Scientists consider this may occasionally be partly because immunity has been built up through vaccinations and infections.

“Since then, we continue to see these different subvariants of Omicron accumulating more and more different mutations,” Long said. “Right now everything seems to be fixed on this omicron branch of the tree.”

The Omicron relative now dominant within the U.S. is named XEC and accounted for 45% of the variants circulating nationwide within the two-week period ending Dec. 21 CDC said. Existing COVID-19 drugs and the newest vaccine booster needs to be effective against it, Long said, because it is “actually a kind of remixing of variants that are already circulating.”

What can we find out about long COVID?

Millions of individuals remain in limbo with a sometimes disabling, often invisible legacy of the pandemic called Long-COVID.

After a bout of COVID-19, it may well take several weeks for the disease to rebound, but some people experience more persistent problems. Symptoms, which last at the very least three months and sometimes even years, include fatigue, cognitive impairment, so-called “brain fog”, pain and cardiovascular problems.

Doctors don't know why just some people get long COVID. It can occur even after a light course and at any age, although the incidence has decreased for the reason that early years of the pandemic. Studies show that vaccination can reduce the danger.

It's also not clear what causes long COVID, making it difficult to search out treatments. An essential note: More and more researchers are discovering that remnants of the coronavirus can remain within the bodies of some patients long after the initial infection, although this cannot explain all cases.

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The Associated Press Health and Science Department receives support from the Science and Educational Media Group of the Howard Hughes Medical Institute. The AP is solely accountable for all content.

Originally published: January 3, 2025 at 6:45 am PST